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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - dllexported dtor and virtual base lead to undefined symbol in debug build"
href="https://bugs.llvm.org/show_bug.cgi?id=44035">44035</a>
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<th>Summary</th>
<td>dllexported dtor and virtual base lead to undefined symbol in debug build
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Windows NT
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>-New Bugs
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>oktal3700@gmail.com
</td>
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<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
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<pre>Created <span class=""><a href="attachment.cgi?id=22829" name="attach_22829" title="repro testcase">attachment 22829</a> <a href="attachment.cgi?id=22829&action=edit" title="repro testcase">[details]</a></span>
repro testcase
When compiling the same code with clang-cl (r375090) and MSVS 2019 (16.3.9),
the LLVM toolchain fails with a linker error, while the Microsoft one does not.
error : undefined symbol: __declspec(dllimport) public: void __thiscall
derived::`vbase dtor'(void)
Full repro below (also in the attachment)
=== lib.h ===
struct base {
virtual LIBRARY_EXPORT ~base();
};
struct derived : public virtual base {
virtual LIBRARY_EXPORT ~derived();
};
=== lib.cpp ===
#define LIBRARY_EXPORT __declspec(dllexport)
#include "lib.h"
LIBRARY_EXPORT base::~base() = default;
LIBRARY_EXPORT derived::~derived() = default;
=== main.cpp ===
#define LIBRARY_EXPORT __declspec(dllimport)
#include "lib.h"
int main() {
derived{};
}
================
LLVM toolchain commands:
<span class="quote">> clang-cl /c /Z7 /W3 /WX- /Od /D _WINDLL /D _MBCS /EHsc /MDd /GS /Gd /TP lib.cpp
> lld-link /OUT:"library.dll" /IMPLIB:"library.lib" /DLL lib.obj
> clang-cl /c /Z7 /W3 /WX- /Od /D _MBCS /EHsc /MDd /GS /Gd /TP main.cpp
> lld-link /OUT:"executable.exe" library.lib main.obj</span >
Output:
lld-link : error : undefined symbol: __declspec(dllimport) public: void
__thiscall derived::`vbase dtor'(void)
<span class="quote">>>> referenced by D:\Mat\Projects\test\executable\main.cpp:5
>>> Debug\main.obj:(_main)
>>> referenced by D:\Mat\Projects\test\library\lib.h:14
>>> Debug\main.obj:(public: virtual void * __thiscall derived::`scalar deleting dtor'(unsigned int))</span >
The same commands with the Microsoft toolchain, giving no errors:
<span class="quote">> cl /c /Z7 /W3 /WX- /Od /D _WINDLL /D _MBCS /EHsc /MDd /GS /Gd /TP lib.cpp
> link /OUT:"library.dll" /IMPLIB:"library.lib" /DLL lib.obj
> cl /c /Z7 /W3 /WX- /Od /D _MBCS /EHsc /MDd /GS /Gd /TP main.cpp
> link /OUT:"executable.exe" library.lib main.obj</span >
I've also tried the release binaries of LLVM 8 and 9 and the same issue is
present.</pre>
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